1. Field of the Invention
The present invention is directed to an improved wheel assembly of the type which includes a hub rotatable about a spindle, wherein the hub includes a bearing stop shoulder and, more specifically, a bearing spacer located between the hub and the spindle which is designed to reduce stress concentrations in the bearing stop shoulder area of the hub.
2. Description of the Prior Art
The prior art is best illustrated by U.S. Pat. Nos. 3,726,576 to Barnbrook et al issued Apr. 10, 1973; 3,515,448 to C. W. Williams et al issued June 2, 1970; 3,765,737 to Hatch issued Oct. 16, 1973; 3,156,506 to H. B. Scheifele et al issued Nov. 10, 1964 and 4,085,984 to R. W. Cameron issued Apr. 25, 1978. These patents show bearings which have inner and outer races with a sharp radaii of curvatures in intimate contact with bearing stop shoulders. It has been found that these designs worked adequately in heavy duty axle assemblies. More specifically, these designs are acceptable for hubs and shafts made out of steel.
The present invention is directed to wheel assemblies which have hubs made of aluminum rather than of steel. The use of aluminum hubs reduces the weight of the vehicle thus permitting more economical operation thereof. It has been found, however, that using lightweight aluminum hubs in high stress situations has caused cracking of the hub in the area of the bearing stop shoulder. This stress cracking was not found in stronger, heavier steel hubs of similar design. The present invention is designed to reduce the stress concentration at the bearing stop shoulders on the aluminum hubs thereby making the use of aluminum hubs in heavy duty vehicles far more reliable.
U.S. Pat. No. 3,156,506 to H. B. Scheifele et al is typical of the prior art applications in which the bearings have sharp radaii on the corners of their inner and outer races which make close contact with the hub assembly and the shaft assembly. The main concern of the present invention is with the hub and, consequently, the outer race of the bearing. In order to use standard bearings, it has been found necessary to use a bearing spacer to allow a greater radius of curvature on the bearing stop shoulder of the hub. The bearing stop spacer is placed between the outer surface of the bearing and the inner surface of the bearing stop shoulder which provides a corner radius much larger than that of the standard bearing such as that shown in Scheifele et al.